[jira] [Commented] (HBASE-16302) age of last shipped op and age of last applied op should be histograms

["Ted Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-16302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15685066#comment-15685066 ] 

Ted Yu commented on HBASE-16302:
--------------------------------

lgtm

> age of last shipped op and age of last applied op should be histograms
> ----------------------------------------------------------------------
>
>                 Key: HBASE-16302
>                 URL: https://issues.apache.org/jira/browse/HBASE-16302
>             Project: HBase
>          Issue Type: Improvement
>          Components: Replication
>            Reporter: Ashu Pachauri
>            Assignee: Ashu Pachauri
>             Fix For: 2.0.0, 1.4.0, 1.3.1
>
>         Attachments: HBASE-16302.patch.v0.patch
>
>
> Replication exports metric ageOfLastShippedOp as an indication of how much replication is lagging. But, with multiwal enabled, it's not representative because replication could be lagging for a long time for one wal group (something wrong with a particular region) while being fine for others. The ageOfLastShippedOp becomes a useless metric for alerting in such a case.
> Also, since there is no mapping between individual replication sources and replication sinks, the age of last applied op can be a highly spiky metric if only certain replication sources are lagging.
> We should use histograms for these metrics and use maximum value of this histogram to report replication lag when building stats.



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